Women who work nightshifts may face a higher risk of developing moderate or severe asthma compared to those working in the daytime, according to a new study involving more than 270,000 individuals.
The research, published in ERJ Open Research, found that women who worked only nightshifts were around 50 percent more likely to suffer from moderate or severe asthma than women who worked only during the day.
In contrast, the study found no similar association between asthma and shift timing among men.
Researchers from the University of Manchester, UK, analysed data from 274,541 working individuals. Among them, 5.3 percent were diagnosed with asthma, and 1.9 percent had moderate or severe forms of the disease, which was defined as using a preventer inhaler and at least one other asthma treatment such as an oral steroid.
The study revealed that overall, women who work shifts were more likely to have asthma than those who do not.
The study builds on earlier research which had already suggested a link between nightshift work and increased asthma risk.
However, this is the first study to explore how this relationship differs between men and women. The findings highlighted that women tend to experience more severe asthma and have higher hospitalisation and death rates due to the condition compared to men.
Although the exact cause behind the link remains unclear, researchers noted that it might be related to the disruption of the body’s internal clock caused by shift work. This disruption may affect the levels of sex hormones, which are known to influence asthma risk.
Previous studies have shown that testosterone can be protective against asthma, which could explain why women, who have lower testosterone levels, are more affected.
The study also found that postmenopausal women not taking hormone replacement therapy were almost twice as likely to suffer from moderate or severe asthma if they worked nightshifts compared to those working during the day. This suggests that hormone levels may play a significant role in the observed risk.
Researchers stated that further studies are needed to investigate the role of sex hormones in the connection between shift work and asthma. They plan to conduct future research, including prospective studies and randomised controlled trials, to better understand the underlying mechanisms.
